Signatures of adaptation at key insecticide resistance loci in Anopheles gambiae in Southern Ghana revealed by reduced-coverage WGS.

Resistance to insecticides and adaptation to a diverse range of environments present challenges to Anopheles gambiae s.l. mosquito control efforts in sub-Saharan Africa. Whole-genome-sequencing is often employed for identifying the genomic basis underlying adaptation in Anopheles, but remains expensive for large-scale surveys. Reduced coverage whole-genome-sequencing can identify regions of the genome involved in adaptation at a lower cost, but is currently untested in Anopheles mosquitoes. Here, we use reduced coverage WGS to investigate population genetic structure and identify signatures of local adaptation in Anopheles mosquitoes across southern Ghana. In contrast to previous analyses, we find no structuring by ecoregion, with Anopheles coluzzii and Anopheles gambiae populations largely displaying the hallmarks of large, unstructured populations. However, we find signatures of selection at insecticide resistance loci that appear ubiquitous across ecoregions in An. coluzzii, and strongest in forest ecoregions in An. gambiae. Our study highlights resistance candidate genes in this region, and validates reduced coverage WGS, potentially to very low coverage levels, for population genomics and exploratory surveys for adaptation in Anopheles taxa.

A molecule-imprinted electrochemiluminescence sensor based on CdS@MWCNTs for ultrasensitive detection of fenpropathrin.

A molecularly-imprinted electrochemiluminescence sensor was constructed for the determination of fenpropathrin (FPT) by molecular imprinting technology. In this sensing platform, the introduction of CdS@MWCNTs significantly enhanced the initial ECL signal of the luminol-O2 system. Specifically, MWCNTs was used as a carrier to adsorb more CdS, in which CdS acted as a co-reaction promoter for luminescence. Molecularly imprinted polymer (MIP) containing specific recognition sites of FPT was used as the material for selective recognition. With increasing amount of FPT the ECL signal decreased. Under the optimum conditions, the ECL response was linearly related to the logarithm of FPT concentration. The developed ECL sensor allowed for sensitive determination of FPT and exhibited a wide linear range from 1.0 × 10- 10 mol L- 1 to 1.0 × 10- 6 mol L- 1. The limit of detection was 3.3 × 10- 11 mol L- 1 (S/N = 3). It can be used for the detection of FPT in vegetable samples.

Toxic responses of environmental concentrations of bifenthrin in larval freshwater snail Bellamya aeruginosa.

Bifenthrin (BF) is ubiquitous in aquatic environments, and studies have indicated that environmental concentrations of BF could cause neurotoxicity and oxidative damage in fish and decrease the abundance of aquatic insects. However, little information is available on the toxicity of BF in freshwater benthic mollusks. Bellamya aeruginosa (B. aeruginosa) is a key benthic fauna species in aquatic ecosystems, and has extremely high economic and ecological values. In this study, larval B. aeruginosa within 24 h of birth were exposed to 0, 30 or 300 ng/L of BF for 30 days, and then the toxic effects from molecular to individual levels were comprehensively evaluated in all the three treatment groups. It was found that BF at 300 ng/L caused the mortality of snails. Furthermore, BF affected snail behaviors, evidenced by reduced crawling distance and crawling speed. The hepatopancreas of snails in the two BF exposure groups showed significant pathological changes, including increase in the number of yellow granules and occurrence of hemocyte infiltration, epithelial cell thinning, and necrosis. The levels of ROS and MDA were significantly increased after exposure to 300 ng/L BF, and the activities of two antioxidant enzymes SOD and CAT were increased significantly. GSH content decreased significantly after BF exposure, indicating the occurrence of oxidative damage in snails. Transcriptomic results showed that differentially expressed genes (DEGs) were significantly enriched in pathways related to metabolism and neurotoxicity (e.g., oxidative phosphorylation and Parkinson disease), and these results were consistent with those in individual and biochemical levels above. The study indicates that environmental concentration of BF results in decreased survival rates, sluggish behavior, histopathological lesions, oxidative damage, and transcriptomic changes in the larvae of B. aeruginosa. Thus, exposure of larval snails to BF in the wild at concentrations similar to those used in this study might have adverse consequences at the population level. These findings provide a theoretical basis for further assessing the ecological risk of BF to aquatic gastropods.

Laboratory evaluation of the contact irritancy of a clothianidin solo formulation vs. clothianidin-deltamethrin mixture formulations for indoor residual spraying against pyrethroid-resistant Anopheles gambiae sensu lato.

BACKGROUND: Clothianidin-based indoor residual spraying (IRS) formulations have become available for malaria control as either solo formulations of clothianidin or a mixture of clothianidin with the pyrethroid deltamethrin. While both formulations have been successfully used for malaria control, studies investigating the effect of the pyrethroid in IRS mixtures may help improve our understanding for development of future IRS products. It has been speculated that the irritant effect of the pyrethroid in the mixture formulation may result in shorter mosquito contact times with the treated walls potentially leading to a lower impact. METHODS: We compared contact irritancy expressed as the number of mosquito take-offs from cement surfaces treated with an IRS formulation containing clothianidin alone (SumiShield® 50WG) to clothianidin-deltamethrin mixture IRS formulations against pyrethroid-resistant Anopheles gambiae sensu lato under controlled laboratory conditions using a modified version of the World Health Organisation cone bioassay. To control for the pyrethroid, comparison was made with a deltamethrin-only formulation. Both commercial and generic non-commercial mixture formulations of clothianidin and deltamethrin were tested. RESULTS: The clothianidin solo formulation did not show significant contact irritancy relative to the untreated control (3.5 take-offs vs. 3.1 take-offs, p = 0.614) while all deltamethrin-containing IRS induced significant irritant effects. The number of take-offs compared to the clothianidin solo formulation (3.5) was significantly higher with the commercial clothianidin-deltamethrin mixture (6.1, p = 0.001), generic clothianidin-deltamethrin mixture (7.0, p < 0.001), and deltamethrin-only (8.2, p < 0.001) formulations. The commercial clothianidin-deltamethrin mixture induced similar contact irritancy as the generic clothianidin-deltamethrin mixture (6.1 take-offs vs. 7.0 take-offs, p = 0.263) and deltamethrin-only IRS (6.1 take-offs vs. 8.2, p = 0.071), showing that the irritant effect in the mixture was attributable to its deltamethrin component. CONCLUSIONS: This study provides evidence that the enhanced contact irritancy of the pyrethroid in clothianidin-deltamethrin IRS mixtures can shorten mosquito contact times with treated walls compared to the clothianidin solo formulation. Further trials are needed to directly compare the efficacy of these formulation types under field conditions and establish the impact of this enhanced contact irritancy on the performance of IRS mixture formulations containing pyrethroids.

Exploring the relationship between flumethrin resistance and Anaplasma marginale infection in Rhipicephalus (Boophilus) microplus ticks of cattle.

The study explores the relationship between flumethrin resistance and Anaplasma marginale infection in Rhipicephalus (Boophilus) microplus of cattle in South Gujarat, India. Adult Immersion Test (AIT) was used to assess flumethrin resistance and polymerase chain reaction (PCR) to confirm A. marginale infection. Species-specific PCR resulted in the amplification of 576 bp of msp5 gene of A. marginale in 17.69% (49/277) groups of ticks, and subsequent digestion with EcoRI cleaved it into two distinct segments. Navsari district, noted level Ι resistance [resistance factors (RF) = 1.78-3.34], and A. marginale prevalence was 16.67, 15.38, 23.08, 15.38, and 11.76% in Navsari, Jalalpore, Gandevi, Chikhli, and Vansda sub-districts, respectively. Similarly, Vyara and Dolvan sub-districts of Tapi observed level Ι resistance (RF = 1-3.63), with A. marginale positivity of 21.43 and 22.22%, while Valod and Songhad demonstrated susceptibility, with 14.29 and 12.50% of A. marginale, respectively. Moving to Surat, the Mahuva, Bardoli, Mandvi, Palsana, and Kamrej sub-districts observed the level Ι resistance (RF = 1.94-2.89), coupled with 14.29, 17.65, 20, 20, and 21.43% of A. marginale, respectively. Lastly, in Valsad district, Dharampur, Kaparada, Valsad, and Umbergaon noted level Ι resistance (RF = 1.67-1.81), and corresponding A. marginale positivity rates of 18.18, 19.23, 15.00, and 20.00%. The scatter plot unveiled a significant moderate positive correlation between RF and A. marginale positivity% (p = 0.0362), characterized by a Pearson correlation coefficient (r) of 0.4963. The covariance (1.1814) highlighted fluctuations, while the coefficient of determination (r2) (0.2463) clarified that 24.63% of the variability in A. marginale positivity% could be attributed to the RF.

Mapping malaria vectors and insecticide resistance in a high-endemic district of Haryana, India: implications for vector control strategies.

BACKGROUND: Achieving effective control and elimination of malaria in endemic regions necessitates a comprehensive understanding of local mosquito species responsible for malaria transmission and their susceptibility to insecticides. METHODS: The study was conducted in the highly malaria prone Ujina Primary Health Center of Nuh (Mewat) district of Haryana state of India. Monthly entomological surveys were carried out for adult mosquito collections via indoor resting collections, light trap collections, and pyrethrum spray collections. Larvae were also collected from different breeding sites prevalent in the region. Insecticide resistance bioassay, vector incrimination, blood meal analysis was done with the collected vector mosquitoes. RESULTS: A total of 34,974 adult Anopheles mosquitoes were caught during the survey period, out of which Anopheles subpictus was predominant (54.7%). Among vectors, Anopheles stephensi was predominant (15.5%) followed by Anopheles culicifacies (10.1%). The Human Blood Index (HBI) in the case of An. culicifacies and An. stephensi was 6.66 and 9.09, respectively. Vector incrimination results revealed Plasmodium vivax positivity rate of 1.6% for An. culicifacies. Both the vector species were found resistant to DDT, malathion and deltamethrin. CONCLUSION: The emergence of insecticide resistance in both vector species, compromises the effectiveness of commonly used public health insecticides. Consequently, the implementation of robust insecticide resistance management strategies becomes imperative. To effectively tackle the malaria transmission, a significant shift in vector control strategies is warranted, with careful consideration and adaptation to address specific challenges encountered in malaria elimination efforts.

Mutations and intron polymorphisms in voltage-gated sodium channel genes of different geographic populations of Culex pipiens pallens/Culex pipiens quinquefasciatus in China.

BACKGROUND: Culex pipiens pallens and Culex pipiens quinquefasciatus are the dominant species of Culex mosquitoes in China and important disease vectors. Long-term use of insecticides can cause mutations in the voltage-gated sodium channel (vgsc) gene of mosquitoes, but little is known about the current status and evolutionary origins of vgsc gene in different geographic populations. Therefore, this study aimed to determine the current status of vgsc genes in Cx. p. pallens and Cx. p. quinquefasciatus in China and to investigate the evolutionary inheritance of neighboring downstream introns of the vgsc gene to determine the impact of insecticides on long-term evolution. METHODS: Sampling was conducted from July to September 2021 in representative habitats of 22 provincial-level administrative divisions in China. Genomic DNA was extracted from 1308 mosquitoes, the IIS6 fragment of the vgsc gene on the nerve cell membrane was amplified using polymerase chain reaction, and the sequence was used to evaluate allele frequency and knockdown resistance (kdr) frequency. MEGA 11 was used to construct neighbor-joining (NJ) tree. PopART was used to build a TCS network. RESULTS: There were 6 alleles and 6 genotypes at the L1014 locus, which included the wild-type alleles TTA/L and CTA/L and the mutant alleles TTT/F, TTC/F, TCT/S and TCA/S. The geographic populations with a kdr frequency less than 20.00% were mainly concentrated in the regions north of 38° N, and the geographic populations with a kdr frequency greater than 80.00% were concentrated in the regions south of 30° N. kdr frequency increased with decreasing latitude. And within the same latitude, the frequency of kdr in large cities is relatively high. Mutations were correlated with the number of introns. The mutant allele TCA/S has only one intron, the mutant allele TTT/F has three introns, and the wild-type allele TTA/L has 17 introns. CONCLUSIONS: Cx. p. pallens and Cx. p. quinquefasciatus have developed resistance to insecticides in most regions of China. The neighboring downstream introns of the vgsc gene gradually decreased to one intron with the mutation of the vgsc gene. Mutations may originate from multiple mutation events rather than from a single origin, and populations lacking mutations may be genetically isolated.

Effects of dietary garlic (Allium sativum) oil on growth performance, haemato-biochemical and histopathology of cypermethrin-intoxicated Nile tilapia (Oreochromis niloticus).

BACKGROUND: When pesticides are introduced into wetlands by agriculture, fish quickly absorb them through their gills. Pesticides reduce hatchability, impede growth, and antioxidant response, killing fish. Therefore, it's crucial to find effective pesticide mitigation methods for fish. OBJECTIVE: In this study, the effects of garlic (Allium sativum) oil on the growth, haematology, biochemistry and histopathology parameters of Nile tilapia (Oreochromis niloticus) exposed to cypermethrin toxicity were investigated. METHODS: In the research, cypermethrin was added to the water of the experimental groups at a rate of 1:20 of the LC50 value, and 1.00% garlic oil was added to the fish feed. Fish with an initial weight of 30.26 ± 0.26 g were fed for 45 days. RESULTS: At the end of feeding, the final weights were determined as 69.39 ± 0.41 (G1), 61.81 ± 0.65 (G2), 82.25 ± 0.36 (G3), and 75.04 ± 0.68 (G4) grams, respectively. Histopathological examinations revealed serious lesions in the gill, liver, brain, and muscle tissues in the cypermethrin group, whereas these lesions were minimal or absent in the garlic oil group. CONCLUSIONS: Garlic oil supplementation had positive effects on growth, haematology, blood biochemistry, hepatosomatic index and histopathological parameters. These findings suggest that garlic oil is a potential protective agent against cypermethrin toxicity.

Mycotransformation of Commercial Grade Cypermethrin Dispersion by Aspergillus terreus PDB-B Strain Isolated from Lake Sediments of Kulamangalam, Madurai.

A fungal isolate Aspergillus terreus PDB-B (accession number: MT774567.1), which could tolerate up to 500 mg/L of cypermethrin, was isolated from the lake sediments of Kulamangalam tropical lake, Madurai, and identified by internal transcribed spacer (ITS) sequencing followed by phylogenetic analysis. The biotransformation potential of the strain was compared with five other strains (A, J, UN2, M1 and SM108) as a consortium, which were tentatively identified as Aspergillus glaucus, Aspergillus niger, Aspergillus flavus, Aspergillus terreus, and Aspergillus flavus, respectively. Batch culture and soil microcosm studies were conducted to explore biotransformation using plate-based enzymatic screening and GC-MS. A mycotransformation pathway was predicted based on a comparative analysis of the transformation products (TPs) obtained. The cytotoxicity assay revealed that the presence of (3-methylphenyl) methanol and isopropyl ether could be relevant to the high rate of lethality.

Heterologous expression, biochemical characterization and prospects for insecticide biosensing potential of carboxylesterase Ha006a from Helicoverpa armigera.

Enzymes have attracted considerable scientific attention for their crucial role in detoxifying a wide range of harmful compounds. In today's global context, the extensive use of insecticides has emerged as a significant threat to the environment, sparking substantial concern. Insects, including economically important pests like Helicoverpa armigera, have developed resistance to conventional pest control methods through enzymes like carboxyl/cholinesterases. This study specifically focuses on a notable carboxyl/cholinesterase enzyme from Helicoverpa armigera (Ha006a), with the goal of harnessing its potential to combat environmental toxins. A total of six insecticides belonging to two different classes displayed varying inhibitory responses towards Ha006a, thereby rendering it effective in detoxifying a broader spectrum of insecticides. The significance of this research lies in discovering the bioremediation property of Ha006a, as it hydrolyzes synthetic pyrethroids (fenvalerate, λ-cyhalothrin and deltamethrin) and sequesters organophosphate (paraoxon ethyl, profenofos, and chlorpyrifos) insecticides. Additionally, the interaction studies between organophosphate insecticides and Ha006a helped in the fabrication of a novel electroanalytical sensor using a modified carbon paste electrode (MCPE). This sensor boasts impressive sensitivity, with detection limits of 0.019 µM, 0.15 µM, and 0.025 µM for paraoxon ethyl, profenofos, and chlorpyrifos, respectively. This study provides a comprehensive biochemical and biophysical characterization of the purified esterase Ha006a, showcasing its potential to remediate different classes of insecticides.

Transcriptomic analysis of Anopheles gambiae from Benin reveals overexpression of salivary and cuticular proteins associated with cross-resistance to pyrethroids and organophosphates.

BACKGROUND: Insecticide resistance (IR) is one of the major threats to malaria vector control programs in endemic countries. However, the mechanisms underlying IR are poorly understood. Thus, investigating gene expression patterns related to IR can offer important insights into the molecular basis of IR in mosquitoes. In this study, RNA-Seq was used to characterize gene expression in Anopheles gambiae surviving exposure to pyrethroids (deltamethrin, alphacypermethrin) and an organophosphate (pirimiphos-methyl). RESULTS: Larvae of An. gambiae s.s. collected from Bassila and Djougou in Benin were reared to adulthood and phenotyped for IR using a modified CDC intensity bottle bioassay. The results showed that mosquitoes from Djougou were more resistant to pyrethroids (5X deltamethrin: 51.7% mortality; 2X alphacypermethrin: 47.4%) than Bassila (1X deltamethrin: 70.7%; 1X alphacypermethrin: 77.7%), while the latter were more resistant to pirimiphos-methyl (1.5X: 48.3% in Bassila and 1X: 21.5% in Djougou). RNA-seq was then conducted on resistant mosquitoes, non-exposed mosquitoes from the same locations and the laboratory-susceptible An. gambiae s.s. Kisumu strain. The results showed overexpression of detoxification genes, including cytochrome P450s (CYP12F2, CYP12F3, CYP4H15, CYP4H17, CYP6Z3, CYP9K1, CYP4G16, and CYP4D17), carboxylesterase genes (COEJHE5E, COE22933) and glutathione S-transferases (GSTE2 and GSTMS3) in all three resistant mosquito groups analyzed. Genes encoding cuticular proteins (CPR130, CPR10, CPR15, CPR16, CPR127, CPAP3-C, CPAP3-B, and CPR76) were also overexpressed in all the resistant groups, indicating their potential role in cross resistance in An. gambiae. Salivary gland protein genes related to 'salivary cysteine-rich peptide' and 'salivary secreted mucin 3' were also over-expressed and shared across all resistant groups. CONCLUSION: Our results suggest that in addition to metabolic enzymes, cuticular and salivary gland proteins could play an important role in cross-resistance to multiple classes of insecticides in Benin. These genes warrant further investigation to validate their functional role in An. gambiae resistance to insecticides.

Adverse effects of fenpropathrin on the intestine of common carp (Cyprinus carpio L.) and the mechanism involved.

Fenpropathrin (FEN), a pyrethroid pesticide, is frequently detected in natural water bodies, unavoidable pose adverse effects to aquatic organisms. However, the harmful effects and potential mechanisms of FEN on aquatic species are poorly understood. In this study, common carp were treatment with FEN at 0.45 and 1.35 µg/L for 14 d, and the toxic effects and underlying mechanisms of FEN on the intestine of carp were revealed. RNA-seq results showed that FEN exposure cause a wide range of transcriptional alterations in the intestine and the differentially expressed genes were mainly enrichment in the pathways related to immune and metabolism. Specifically, FEN exposure induced pathological damage and altered submicroscopic structure of the intestine, elevated the levels of Bacteroides fragilis enterotoxin, altered the contents of claudin-1, occludin, and zonula occluden-1 (ZO-1), and causing injury to the intestinal barrier. In addition, inflammation-related index TNF-α in the serum and IL-6 in the intestinal tissues were generally increased after FEN exposure. Moreover, FEN exposure promoted an increase in reactive oxygen species (ROS), altered the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), upregulated the contents of malondialdehyde (MDA) in the intestines. The apoptosis-related parameter cytochrome c, caspase-9, and caspase-3 were significantly altered, indicating that inflammation reaction, oxidative stress, and apoptosis may be involved in the toxic mechanism of FEN on carp. Moreover, FEN treatment also altered the intestinal flora community significantly, which may affect the intestinal normal physiological function and thus affect the growth of fish. Overall, the present study help to clarify the intestinal reaction mechanisms after FEN treatment, and provide a basis for the risk assessment of FEN.

Identification of insect cuticular protein genes LCP17 and SgAbd5 from Helicoverpa armigera and evaluation their roles in fenvalerate resistance.

Insect cuticular protein (ICP) plays an important role in insect growth and development. However, research on the role of ICP in insecticide resistance is very limited. In this study, insect cuticular protein genes LCP17 and SgAbd5 were cloned and characterized in Helicoverpa armigera based on previous transcriptome data. The functions of LCP17 and SgAbd5 genes in fenvalerate resistance were assessed by RNA interference (RNAi), and their response to fenvalerate was further detected. The results showed that LCP17 and SgAbd5 were overexpressed in the fenvalerate-resistant strain comparing with a susceptible strain. The open reading frames of LCP17 and SgAbd5 genes were 423 bp and 369 bp, encoding 141 and 123 amino acids, respectively. LCP17 and SgAbd5 genes were highly expressed in the larval stage, but less expressed in the adult and pupal stages. The expression level of LCP17 and SgAbd5 genes increased significantly after fenvalerate treatment at 24 h. When the cotton bollworms larvae were exposed to fenvalerate at LD50 level, RNAi-mediated silencing of LCP17 and SgAbd5 genes increased the mortality from 50.68% to 68.67% and 63.89%, respectively; the mortality increased to even higher level, which was 73.61%, when these two genes were co-silenced. Moreover, silencing of these two genes caused the cuticle lamellar structure to become loose, which led to increased penetration of fenvalerate into the larvae. The results suggested that LCP17 and SgAbd5 may be involved in the resistance of cotton bollworm to fenvalerate, and LCP17 and SgAbd5 could serve as potential targets for H. armigera control.

Carboxymethyl chitosan-modified UiO-66 for the rapid detection of fenpropathrin in grains.

Fenpropathrin residues in grain are potentially harmful to humans. Therefore, a fluorimetric lateral flow immunoassay using a zirconium-based organic skeleton (UiO-66) as a signal marker was developed for detecting fenpropathrin. Herein, carboxymethyl chitosan (CMCS) was used to modify UiO-66 and improve its water solubility to facilitate stable binding with sodium fluorescein (NaFL). This resulted in formation of a new fluorescent probe that is more suitable for lateral flow immunoassay (LFIA). The materials were characterized via electron microscopy, Fourier-transform infrared spectroscopy, and powder X-ray diffraction. CMCS and NaFL were successfully bound to UiO-66. Under optimized conditions, the constructed NaFL/UiO-66@CMCS-LFIA exhibited a good linear relationship within the range of 0.98-62.5 µg/L, with a detection limit of 3.91 µg/L. This probe was fourfold more sensitive than traditional colloidal gold nanoparticle-based LFIA. Finally, NaFL/UiO-66@CMCS-LFIA was successfully applied to detect fenpropathrin in wheat and maize samples. The detection limit was 1.56 µg/kg and recoveries ranged from 96.58 % to 118.56 %. This study provides a sensitive, stable, and convenient method for the rapid detection of pesticide residues.

Systematic review of clinical manifestations, management and outcome following accidental ingestion of liquid mosquito repellent vaporiser in children.

BACKGROUND: Pyrethroid-based mosquito repellents are widely used to control mosquito-borne diseases. Liquid mosquito-repellent vaporisers are effective modes of pyrethroid delivery but can also pose significant health risks if ingested or used improperly. OBJECTIVE: This systematic review was performed to assess the demographic distribution, clinical presentation, management strategies and outcomes in children resulting from accidental ingestion of liquid mosquito repellent vaporiser. METHODS: The study adheres to the reporting standards outlined in the PRISMA Statement for Systematic Reviews and was prospectively registered with PROSPERO (record # CRD42023413937) to enhance transparency and minimise reporting bias. A comprehensive search was conducted on PubMed, Scopus and Google Scholar using specific MeSH terms related to insecticides, mosquito repellents, pyrethroids, ingestion, poisoning, toxicity and prevention. The reference lists of the included studies were also reviewed for additional relevant articles. The inclusion criteria involved studies published in peer-reviewed journals between 2000 and 2023 that focused on children under 18 years old with a history of mosquito-repellent ingestion based on primary data. RESULTS: Twelve studies met the inclusion criteria; these were primarily case reports from India, China and the UAE. Male children were predominantly affected, and symptoms included vomiting, convulsions, cough and respiratory distress. Management primarily involved supportive and symptomatic measures, including atropine for salivation and antiepileptic drugs for seizures. Respiratory support was provided for respiratory complications. CONCLUSION: Despite the known risks and diverse presentations of pyrethroid poisoning caused by liquid mosquito repellent vaporiser in children, the limited substantial evidence in the literature underscores the urgent need for comprehensive research to refine management approaches and enhance preventive measures.

Associations of pyrethroid exposure with bone mineral density and osteopenia in adults.

INTRODUCTION: This study was to investigate the correlations between pyrethroid exposure and bone mineral density (BMD) and osteopenia. MATERIALS AND METHODS: This cross-sectional study included 1389 participants over 50 years of age drawn from the 2007-2010 and 2013-2014 National Health and Nutrition Examination Survey (NHANES). Three pyrethroid metabolites, 3-phenoxybenzoic acid (3-PBA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid (trans-DCCA), and 4-fluoro-3-phenoxybenzoic acid (4-F-3PBA) were used as indicators of pyrethroid exposure. Low BMD was defined as T-score < - 1.0, including osteopenia. Weighted multivariable linear regression analysis or logistic regression analysis was utilized to evaluate the correlation between pyrethroid exposure and BMD and low BMD. Bayesian kernel machine regression (BKMR) model was utilized to analyze the correlation between pyrethroids mixed exposure and low BMD. RESULTS: There were 648 (48.41%) patients with low BMD. In individual pyrethroid metabolite analysis, both tertile 2 and tertile 3 of trans-DCCA were negatively related to total femur, femur neck, and total spine BMD [coefficient (ß) = - 0.041 to - 0.028; all P < 0.05]. Both tertile 2 and tertile 3 of 4-F-3PBA were negatively related to total femur BMD (P < 0.05). Only tertile 2 [odds ratio (OR) = 1.63; 95% CI = 1.07, 2.48] and tertile 3 (OR = 1.65; 95% CI = 1.10, 2.50) of trans-DCCA was correlated with an increased risk of low BMD. The BKMR analysis indicated that there was a positive tendency between mixed pyrethroids exposure and low BMD. CONCLUSION: In conclusion, pyrethroids exposure was negatively correlated with BMD levels, and the associations of pyrethroids with BMD and low BMD varied by specific pyrethroids, pyrethroid concentrations, and bone sites.

Late gestational exposure to fenvalerate impacts ovarian reserve in neonatal mice via YTHDF2-mediated P-body assembly.

Fenvalerate (FEN), a type II pyrethroid pesticide, finds extensive application in agriculture, graziery and public spaces for pest control, resulting in severe environmental pollution. As an environmental endocrine disruptor with estrogen-like activity, exposure to FEN exhibited adverse effects on ovarian functions. Additionally, the presence of the metabolite of FEN in women's urine shows a positive association with the risk of primary ovarian insufficiency (POI). In mammals, the primordial follicle pool established during the early life serves as a reservoir for storing all available oocytes throughout the female reproductive life. The initial size of the primordial follicle pool and the rate of its depletion affect the occurrence of POI. Nevertheless, there is very limited research about the impact of FEN exposure on primordial folliculogenesis. In this study, pregnant mice were orally administrated with 0.2, 2.0 and 20.0 mg/kg FEN from 16.5 to 18.5 days post-coitus (dpc). Ovaries exposed to FEN exhibited the presence of large germ-cell cysts that persist on 1 days post-parturition (1 dpp), followed by a significant reduction in the total number of oocytes in pups on 5 dpp. Moreover, the levels of m6A-RNA and its associated proteins METTL3 and YTHDF2 were significantly increased in the ovaries exposed to FEN. The increased YTHDF2 promoted the assembly of the cytoplasmic processing bodies (P-body) in the oocytes, accompanied with altered expression of transcripts. Additionally, when YTHDF2 was knocked-down in fetal ovary cultures, the primordial folliculogenesis disrupted by FEN exposure was effectively restored. Further, the female offspring exposed to FEN displayed ovarian dysfunctions reminiscent of POI in early adulthood, characterized by decreases in ovarian coefficient and female hormone levels. Therefore, the present study revealed that exposure to FEN during late pregnancy disrupted primordial folliculogenesis by YTHDF2-mediated P-body assembly, causing enduring adverse effects on female fertility.

Temperature, mosquito feeding status and mosquito density influence the measured bio-efficacy of insecticide-treated nets in cone assays.

BACKGROUND: The WHO cone bioassay is routinely used to evaluate the bioefficacy of insecticide-treated nets (ITNs) for product pre-qualification and confirmation of continued ITN performance during operational monitoring. Despite its standardized nature, variability is often observed between tests. We investigated the influence of temperature in the testing environment, mosquito feeding status and mosquito density on cone bioassay results. METHODS: Cone bioassays were conducted on MAGNet (alphacypermethrin) and Veeralin (alphacypermethrin and piperonyl butoxide (PBO)) ITNs, using laboratory-reared pyrethroid-resistant Anopheles funestus sensu stricto (FUMOZ strain) mosquitoes. Three experiments were conducted using standard cone bioassays following WHO-recommended test parameters, with one variable changed in each bioassay: (i) environmental temperature during exposure: 22-23 °C, 26-27 °C, 29-30 °C and 32-33 °C; (ii) feeding regimen before exposure: sugar starved for 6 h, blood-fed or sugar-fed; and (iii) mosquito density per cone: 5, 10, 15 and 20 mosquitoes. For each test, 15 net samples per treatment arm were tested with four cones per sample (N = 60). Mortality after 24, 48 and 72 h post-exposure to ITNs was recorded. RESULTS: There was a notable influence of temperature, feeding status and mosquito density on An. funestus mortality for both types of ITNs. Mortality at 24 h post-exposure was significantly higher at 32-33 °C than at 26-27 °C for both the MAGNet [19.33% vs 7%; odds ratio (OR): 3.96, 95% confidence interval (CI): 1.99-7.87, P < 0.001] and Veeralin (91% vs 47.33%; OR: 22.20, 95% CI: 11.45-43.05, P < 0.001) ITNs. Mosquito feeding status influenced the observed mortality. Relative to sugar-fed mosquitoes, The MAGNet ITNs induced higher mortality among blood-fed mosquitoes (7% vs 3%; OR: 2.23, 95% CI: 0.94-5.27, P = 0.068) and significantly higher mortality among starved mosquitoes (8% vs 3%, OR: 2.88, 95% CI: 1.25-6.63, P = 0.013); in comparison, the Veeralin ITNs showed significantly lower mortality among blood-fed mosquitoes (43% vs 57%; OR: 0.56, 95% CI: 0.38-0.81, P = 0.002) and no difference for starved mosquitoes (58% vs 57%; OR: 1.05, 95% CI: 0.72-1.51, P = 0.816). Mortality significantly increased with increasing mosquito density for both the MAGNet (e.g. 5 vs 10 mosquitoes: 7% vs 12%; OR: 1.81, 95% CI: 1.03-3.20, P = 0.040) and Veeralin (e.g. 5 vs 10 mosquitoes: 58% vs 71%; OR 2.06, 95% CI: 1.24-3.42, P = 0.005) ITNs. CONCLUSIONS: The results of this study highlight that the testing parameters temperature, feeding status and mosquito density significantly influence the mortality measured in cone bioassays. Careful adherence to testing parameters outlined in WHO ITN testing guidelines will likely improve the repeatability of studies within and between product testing facilities.

Multifaceted Effects of Subchronic Exposure to Chlorfenapyr in Mice: Implications from Serum Metabolomics, Hepatic Oxidative Stress, and Intestinal Homeostasis.

As chlorfenapyr is a commonly used insecticide in agriculture, the health risks of subchronic exposure to chlorfenapyr remained unclear. This study aimed to extensively probe the health risks from subchronic exposure to chlorfenapyr at the NOAEL and 10-fold NOAEL dose in mice. Through pathological and biochemical examinations, the body metabolism, hepatic toxicity, and intestinal homeostasis were systematically assessed. After 12 weeks, a 10-fold NOAEL dose of chlorfenapyr resulted in weight reduction, increased daily food intake, and blood lipid abnormalities. Concurrently, this dosage induced hepatotoxicity and amplified oxidative stress in hepatocytes, a finding further supported in HepG2 cells. Moreover, chlorfenapyr resulted in intestinal inflammation, evidenced by increased inflammatory factors (IL-17a, IL-10, IL-1ß, IL-6, IL-22), disrupted immune cells (RORγt, Foxp3), and compromised intestinal barriers (ZO-1 and occludin). By contrast, the NOAEL dose presented less toxicity in most evaluations. Serum metabolomic analyses unveiled widespread disruptions in pathways related to hepatotoxicity and intestinal inflammation, including NF-κB signaling, Th cell differentiation, and bile acid metabolism. Microbiomic analysis showed an increase in Lactobacillus, a decrease in Muribaculaceae, and diminished anti-inflammatory microbes, which further propelled the inflammatory response and leaded to intestinal inflammation. These findings revealed the molecular mechanisms underlying chlorfenapyr-induced hepatotoxicity and intestinal inflammation, highlighting the significant role of the gut microbiota.